OBJECTIVE: To investigate the usefulness of carotid ultrasound evaluation in predicting the presence and the extent of coronary artery disease in a consecutive series of patients. DESIGN: We examined retrospectively 1337 patients in whom both coronary angiography and carotid ultrasound were evaluated, from 1995 to 2005. Markers of carotid artery disease were considered, such as intima-media thickness more than 0.90 mm, unstable plaque and severe stenosis (> or =70%). Carotid risk score was defined as the sum of these parameters. We considered as affected by significant coronary artery disease those patients with at least one lesion more than 50% within the main branches of the coronary arteries. RESULTS: The markers of carotid atherosclerosis increased proportionally in patients with one-, two- or three-vessel coronary artery disease. At univariate analysis, intima-media thickness more than 0.90 mm was associated with an odds ratio of coronary artery disease of 2.28 (1.8-2.9) (P < 0.0001), unstable plaque 3.6 (2.3-5.7) (P < 0.001) and severe carotid stenosis 4.2 (2.0-8.7) (P = 0.0001). At multivariate analysis, the three markers mentioned above were independent risk factors for coronary artery disease even when considering other risk factors. CONCLUSION: We confirmed the usefulness of carotid ultrasound evaluation in predicting the presence and extent of coronary artery disease. Considering the high correlation between carotid and coronary artery disease, carotid screening is useful in patients with coronary artery disease. In patients with an occasional finding of a carotid risk score of at least 2, a careful search for coronary artery disease seems warranted.